are relatively inexpensive (~$150/kWe). A substantial heat or chemical transport subsystem is required for central electric generation. The extra costs and losses of this subsystem must be traded off against the lower costs of the central Rankine plant. The second approach is distributed generation where the heat engine is located near the dish. Electric power is generated at each dish and collected at a central site for external transmission. This second approach can use much higher temperatures since there is a very short (~10's of feet) heat transport line to the heat engine. Energy conversion devices which are suitable at high temperatures (> 500°C) are gas Brayton engines, Stirling engines, advanced liquid metal Rankine systems, and thermionic conversion devices. In this study only the closed cycle Brayton engine is considered. The approach evaluated for distributed generation in this study considers only a small amount of power produced at each dish (—20 kW). The small heat engines tend to be expensive and less efficient than large central heat engines. This disadvantage may be partially alleviated by grouping a small number of dish collectors to provide energy to a larger heat engine. The modular approach of the distributed generation system has the advantage of partial power production early in construction. This tends to minimize the costs of tying up capital for a long construction period with interest, escalation and startup difficulties. The other advantage of a modular distributed generation is that small, irregular parcels of land can be used effectively. This characteristic is most useful in near urban or urban areas where large blocks of land are difficult to assemble, or in newly developing urban areas where land can be put aside for power generation as the area develops. The visual impact is much less for this low profile system compared to centra! tower designs. Finally, the use of a closed cycle Brayton engine has the advantage of high (95-150°C) heat rejection temperatures
RkJQdWJsaXNoZXIy MTU5NjU0Mg==